Recently, I encountered a challenge in my Angular project. As a newcomer to Angular, I was tasked with modifying a directive that handles forms to ensure the submit button is disabled during processing and then enabled again once all operations are complete.
Given that the functions being invoked often involve asynchronous calls, a simple sequential approach did not suffice.
In an attempt to address this issue, I initially implemented the following code snippet:var ngSubmit = function() {
vm.disabled = true;
$scope.ngSubmitFunction();
vm.disabled = false;
}
However, the submit button became enabled before the async calls within `ngSubmitFunction()` had finished.
Upon further consideration, I sought to incorporate promises into the solution, resulting in the following implementation:
var promise = function() {
return $q(function (resolve) {$scope.ngSubmitFunction()});
}
var ngSubmit = function() {
vm.disabled = true;
promise().then(function() {
vm.disabled = false;
});
}
Regrettably, while this modification did not throw any errors, the button remained disabled as the `.then` function was never executed.
I experimented with different approaches for defining promises, yet encountered identical outcomes, except for one particular method:
$scope.submitPromise = function() {
return $q.when($scope.ngSubmitFunction());
}
Although this version did trigger the `.then` function, it still failed to wait for child async functions to complete. The `.then` function seemed to execute instantaneously, much like the original sequential logic.
Considering the unpredictable nature of `ngSubmitFunction()`—which could potentially encompass multiple asynchronous operations—I found myself contemplating alternative strategies. Specifically, how can I effectively chain promises in scenarios involving non-promise functions? Is there a method to ensure certain code executes only after all other processes have concluded?
Within `ngSubmitFunction()`, the flow typically involves:
- Invocation of `func()`
-- Evaluation within `func()` to determine whether to call `create()` or `update()`
-- -- Execution of `update()`, which includes an asynchronous call to `elementFactory.update()`
-- -- -- Triggers `elementFactory.update().then(function())` upon completion
-- -- -- -- It's at this precise juncture that the button should be re-enabled.
How can I achieve this synchronization? Is there a viable approach to integrating events from DataFactory when individual async calls terminate? This scenario raises complications if `update()` initiates multiple asynchronous requests concurrently.